Well, my initial impressions of the Emby native client, as a 'first' time Emby user.

I set up a Mac Mini as Emby Server, rather than mess with a perfectly working PC running Plex.
(Probably my first newbie mistake)

Setup the Mac Emby server, media libraries etc.
Tested media playback on the local host (Mac itself using the web interface) and everything plays fine that I tried.

Tried out Emby client on my iPad, and again everything seemed fine.
Tried out Emby client on the AppleTV4 itself, and it seemed fine.

Tried out MrMC, and had problems connecting to the Mac running Emby server.

Discovered that the Mac Emby server does not ask for user credentials during install, so had to add an emby local account into the server and link that user to Emby account.
(Tho never had to do that for TVOS client or iPad)

After doing the above, MrMC connected to the Mac Emby server, and could access libraries, and see metadata and artwork etc.
However, when selecting a movie, it does not play. I checked the Mac Emby server user rights, and everything was correct, but can not play any media, although the library list showed everything.

Based purely on the media info of my collection of movies and tv shows, Emby does not do as good a job at finding artwork as Plex does. It only found correct artwork for about two thirds of my collection, and just inserted video thumbnails for the rest. Plex did far better at about 95%, and just got confused with classic 60's show Avengers and instead confused it with an animated show Avengers Assemble, and similar occurances.

I guess each has it's prerequisites for media structure, and my collection is more Plex friendly or something.

Speaking purely as a newbie user to Emby, I would just comment that I don't think I will be changing over from Plex anytime soon, and the MrMC built in meta data, artwork does a far better job than Emby for my collection.

I guess Emby requires some more configuration and tweaking, and a bigger investment in time and effort.
People, what are your first impressions of the Emby support, is it working well for you?

Emby login: I think there is something going on there. Will setup a simple emby server on the mac. Both Amet and I are running Emby on QNAP NAS. I also have it setup on a fast linux box. With username/passwords. We found during testflight that Emby permits empty passwords. Maybe also permits an empty username ? Will poke deeper. Assumptions, they kill you every time

Would like to see a debuglog for playing media. It you see the media, it should have an emby token to play it.

As for Plex vs Emby regarding metadata. Agreed, Plex seems to do a much does a much better job. But Emby does ISOs, Plex does not. Media Server wars

Emby login: I think there is something going on there. Will setup a simple emby server on the mac. Both Amet and I are running Emby on QNAP NAS. I also have it setup on a fast linux box. With username/passwords. We found during testflight that Emby permits empty passwords. Maybe also permits an empty username ? Will poke deeper. Assumptions, they kill you every time

Would like to see a debuglog for playing media. It you see the media, it should have an emby token to play it.

As for Plex vs Emby regarding metadata. Agreed, Plex seems to do a much does a much better job. But Emby does ISOs, Plex does not. Media Server wars